Method and apparatus for recycling magnesium alloy cuttings

ABSTRACT

A method and an apparatus for recycling magnesium alloy cuttings are provided. A structure of the apparatus includes: a smelting furnace, configured to hold molten magnesium, where the smelting furnace is segmented into a refining chamber and a molten metal tapping chamber in communication with each other; a mixing unit, rotatably disposed in the refining chamber, and configured to generate a sinking whirlpool toward a bottom of the smelting furnace during rotation; and a waste material treatment unit, including a feeding module, where the feeding module includes a material rod capable of continuously rotating and a material channel in communication with the refining chamber, the material rod is configured to drive magnesium cuttings to enter the refining chamber through the material channel, and the material channel is configured to feed a protective gas.

BACKGROUND Technical Field

The present invention relates to a method and an apparatus for recycling metal, and particularly, to a method and an apparatus for recycling magnesium alloy cuttings.

Related Art

Because of high activity, a magnesium alloy, in a process of recycling a waste material thereof, is likely to burn out and generate massive burning slag, resulting in a low recycling rate and operational difficulty, particularly in regeneration of recycled magnesium alloy cuttings.

Because a magnesium alloy has high activity, a cutting fluid used in mechanical machining is likely to cause magnesium cuttings to ablate rapidly, resulting in a low recycling value. However, if the magnesium cuttings containing the cutting fluid are exposed in the air, not only a gas explosion and a fire may be easily caused, but also because water-containing magnesium cuttings continuously react with nitrogen in the air, ammonia gas or a nitrogen-hydrogen-oxygen compound is generated, causing environmental pollution.

Therefore, industrial magnesium cuttings are considered as industrial waste, and before being cleared, transported, and buried, the industrial magnesium cuttings also need to be stabilized. According to current environmental protection laws and regulations, treatment on magnesium alloy waste includes three stages, namely, intermediate treatment, final disposal, and re-utilization. The intermediate treatment is performing separation, size reduction, detoxification, solidification, or stabilization on a harmful ingredient by using a method such as a physical/chemical/biological method or incineration. The final disposal means sanitary landfill, sealing and landfill, stabilization and landfill, or ocean dumping. The re-utilization means selling or transferring waste or after performing hydrolytic treatment on waste, performing a dissolution test on the waste to make the waste meet standards for utilization.

Currently, commercial regeneration methods for light alloy cuttings include an electromagnetic pump cycling method, a whirlpool well method, and a briquetting method. However, most methods are limited to treating aluminum alloy cuttings, and in terms of applicability to a magnesium alloy, the methods are different according to different sources magnesium cuttings and different objectives.

SUMMARY

A main problem the present invention attempts to resolve is that because of high activity, a magnesium alloy, in a process of recycling a waste material thereof, is likely to burn out and generate massive burning slag, resulting in a low recycling rate and operational difficulty. Therefore, the present invention utilizes a feeding module in combination with a protective gas and a sinking whirlpool to drive magnesium alloy cuttings to rapidly sink and melt, and a rare earth refining agent to protect molten magnesium, so as to re-melt and regenerate the magnesium alloy cuttings.

To achieve the foregoing objective, the present invention discloses an apparatus for recycling magnesium alloy cuttings, where a structure thereof comprises: a smelting furnace, configured to hold molten magnesium, where the smelting furnace is segmented into a refining chamber and a molten metal tapping chamber in communication with each other; a mixing unit, rotatably disposed in the refining chamber, and configured to generate a sinking whirlpool toward a bottom of the smelting furnace during rotation; and a waste material treatment unit, comprising a feeding module, where the feeding module comprises a material rod capable of continuously rotating and a material channel in communication with the refining chamber, the material rod is configured to drive magnesium cuttings to enter the refining chamber through the material channel, and the material channel is configured to feed a protective gas.

In an embodiment, the waste material treatment unit further comprises a heating module and an air intake and dust collection module, where the heating module heats the feeding module, so as to preheat the magnesium alloy cuttings, and the air intake and dust collection module is disposed on the material channel and configured to recycle moisture and oil fume generated by the heated magnesium alloy cuttings.

In the foregoing embodiment, a heat energy source of the heating module is introduced from waste heat generated by the smelting furnace.

In an embodiment, the refining chamber is a cylindrical space.

In an embodiment, the refining chamber comprises a sloping bottom, having an end distal to the molten metal tapping chamber higher than an end proximal to the molten metal tapping chamber.

In this embodiment, the material rod is a screw mechanism.

In an embodiment, the protective gas is a gas mixture of nitrogen and carbon dioxide, where a proportion of nitrogen to carbon dioxide is 1:1.

The present invention also discloses a method for recycling magnesium alloy cuttings, applied to the apparatus for recycling magnesium alloy cuttings as stated above, comprising the following steps: feeding a protective gas into the smelting furnace holding molten magnesium, and adding a rare earth refining agent into the molten magnesium; feeding the protective gas into the material channel, and rotating, by the material rod, to drive magnesium cuttings to enter the refining chamber through the material channel; and rotating, by the mixing unit, to generate a sinking whirlpool, to drive the magnesium cuttings toward a bottom of the smelting furnace, and mixing and dissolving the magnesium cuttings into the molten magnesium, so that magnesium in the magnesium cuttings is separated from slag and magnesium floats upward to the molten metal tapping chamber.

In an embodiment, the waste material treatment unit further comprises a heating module and an air intake and dust collection module, where while feeding the magnesium alloy cuttings into the refining chamber, waste heat of the smelting furnace is introduced to the waste material treatment unit to heat the magnesium alloy cuttings, and oil fume generated after heating the magnesium alloy cuttings is discharged into the air intake and dust collection module for waste gas treatment.

In an embodiment, the molten magnesium in the smelting furnace is generated by melting magnesium blocks fed into the smelting furnace.

In an embodiment, the protective gas fed into the smelting furnace is a gas mixture of sulfur hexafluoride and air, where a flow rate of sulfur hexafluoride is 25 cc/min, and a flow rate of air is 5 L/min.

In an embodiment, the protective gas fed into the material channel is a gas mixture of nitrogen and carbon dioxide, where a flow rate of nitrogen is 1 L/min, and a flow rate of carbon dioxide is 1 L/min.

In an embodiment, the rare earth refining agent may be rare earth, rare earth chloride, or rare earth oxide.

In an embodiment, composition of the rare earth refining agent is 10% cerium oxide mixed with a DOW230 solvent, and an addition amount thereof is 1% of an addition quantity of the magnesium alloy cuttings.

The method and apparatus for recycling magnesium alloy cuttings of the present invention have the following effects: 1. feeding a protective gas into a feeding module, to avoid a gas explosion caused by spill-over and ignition of tiny magnesium alloy cuttings during a process of feeding magnesium alloy cuttings; 2. using a stirrer to generate a sinking whirlpool, to drive the magnesium alloy cuttings, after the magnesium alloy cuttings enter the furnace, to rapidly reach a bottom of the furnace to be molten and separated from slag; and 3. adding rare earth oxide into a refining agent to form a rare earth refining agent, to prevent occurrence of combustion during an operation process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of an apparatus for recycling magnesium alloy cuttings according to the present invention;

FIG. 1B is a schematic structural diagram of a smelting furnace according to the present invention;

FIG. 2A is a schematic flowchart of a method of an embodiment according to the present invention; and

FIG. 2B is a schematic flowchart of a method of another embodiment according to the present invention.

DETAILED DESCRIPTION

A main problem the present invention attempts to resolve is that because of high activity, a magnesium alloy, in a process of recycling a waste material thereof, is likely to be burnt out and generate massive burning slag, resulting in a low recycling rate and operational difficulty. Therefore, the present invention utilizes a feeding module in combination with a protective gas and a sinking whirlpool to drive magnesium alloy cuttings to rapidly sink and melt, and a rare earth refining agent to protect molten magnesium, so as to re-melt and regenerate the magnesium alloy cuttings.

To achieve the foregoing objective, the present invention discloses an apparatus 1 for recycling magnesium alloy cuttings. Referring to FIG. 1A, a structure of the apparatus 1 includes: a smelting furnace 11, segmented into a refining chamber 111 and a molten metal tapping chamber 112 in communication with each other at the bottom, where molten magnesium 10 may be held in the smelting furnace 11; a mixing unit 12, including a stirrer 121 disposed inside the refining chamber 111, where when acting, the stirrer 121 enables the molten magnesium 10 at a position where mixing unit 12 can stir in the refining chamber 111 to drive the molten magnesium 10 inside the refining chamber 111 to form a sinking whirlpool 121A; and a waste material treatment unit 13, including a feeding module 131, where the feeding module 131 includes a material rod 131A capable of continuously rotating and a material channel 131B in communication with the refining chamber 111, the material rod 131A is configured to push magnesium alloy cuttings 2 entering the feeding module 131 to fall into the molten magnesium 10 inside the refining chamber 111, the material channel 131B of the feeding module 131 through which the magnesium alloy cuttings 2 are fed into the molten magnesium 10 is a sealed space, and a protective gas G is fed into the sealed space to prevent the magnesium alloy cuttings 2 from burning.

In this embodiment, the waste material treatment unit 13 further includes a heating module 132 and an air intake and dust collection module 133, where the heating module 132 heats the feeding module 131, so as to preheat the magnesium alloy cuttings 2, and the air intake and dust collection module 133 is disposed on the material channel 131B and configured to recycle waste gas E (including moisture and oil fume) generated by the heated magnesium alloy cuttings 2.

In an embodiment, the heating module 132 is configured to heat the feeding module 131, and a heat energy source of the heating module 132 is introduced from waste heat H generated by melting, by the smelting furnace, magnesium blocks 2A or the magnesium alloy cuttings 2.

In the foregoing embodiment, as shown in FIG. 1B, the refining chamber 111 is a cylindrical space, and a stirrer, as shown in FIG. 1A, is provided to perform rotation and stirring, to generate the sinking whirlpool 121A. The refining chamber 111 and the molten metal tapping chamber 112 are spaced in communication with each other at the bottom inside a smelting furnace 11, and the smelting furnace 11 is configured to increase, after the magnesium blocks 2A are fed into the smelting furnace 11, heat energy to smelt the magnesium blocks 2A into molten magnesium 10.

In this embodiment, the refining chamber 111 includes a sloping bottom, having an end distal to the molten metal tapping chamber 112 higher than an end proximal to the molten metal tapping chamber 112, as shown in FIG. 1A. The sloping bottom is located below the refining chamber 111 having the stirrer 121. Therefore, the sinking whirlpool 121A formed after the stirrer 121 rotates and acts drives the magnesium alloy cuttings 2 falling down from the waste material treatment unit 13 to rapidly sink to the bottom of the smelting furnace 11, accelerates melting of the magnesium alloy cuttings 2, and separates the magnesium alloy cuttings 2 from impurities and slag thereon.

In this embodiment, the material rod 131A is a screw mechanism. In addition, in the material channel 131B, a protective gas G is used to avoid a gas explosion caused by spill-over and ignition of tiny magnesium alloy cuttings 2 during a process of the feeding magnesium alloy cuttings 2. The protective gas is a gas mixture of nitrogen N₂ and carbon dioxide CO₂, where a proportion of nitrogen to carbon dioxide is 1:1.

Subsequently, referring to FIG. 2A, the present invention also discloses a method 51 for recycling magnesium alloy cuttings, applied to the apparatus 1 for recycling magnesium alloy cuttings as stated above, including the following steps:

Step S11: Feed a protective gas into the smelting furnace holding molten magnesium, and add a rare earth refining agent into the molten magnesium.

Step S12: Feed the protective gas into the material channel, and rotate, by the material rod, to drive magnesium cuttings to enter the refining chamber through the material channel.

Step S13: Rotate, by the mixing unit, to generate a sinking whirlpool, to drive the magnesium cuttings toward a bottom of the smelting furnace, and mix and dissolve the magnesium cuttings into the molten magnesium, so that magnesium in the magnesium cuttings is separated from slag and magnesium floats upward to the molten metal tapping chamber.

In this embodiment, as shown in FIG. 2B, the present invention also discloses a method S2 for recycling magnesium alloy cuttings, applied to the apparatus 1 for recycling magnesium alloy cuttings whose waste material treatment unit further includes a heating module 132 and an air intake and dust collection module 133. Steps of recycling magnesium alloy cuttings include:

Step S21: Feed a protective gas into the smelting furnace holding molten magnesium, and add a rare earth refining agent into the molten magnesium.

Step S22A: Feed the protective gas into the material channel, and rotate, by the material rod, to drive magnesium cuttings to enter the refining chamber through the material channel.

Step S22B: Introduce waste heat of the smelting furnace to the waste material treatment unit to heat the magnesium alloy cuttings, and discharge oil fume generated after heating the magnesium alloy cuttings into the air intake and dust collection module for waste gas treatment.

Step S23: Rotate, by the mixing unit, to generate a sinking whirlpool, to drive the magnesium cuttings toward a bottom of the smelting furnace, and mix and dissolve the magnesium cuttings into the molten magnesium, so that magnesium in the magnesium cuttings is separated from slag and magnesium floats upward to the molten metal tapping chamber.

In the method of the embodiment of FIG. 2A, referring to the schematic diagram of the apparatus of FIG. 1A, magnesium blocks 2A are first fed into a smelting furnace 11 to be smelted into molten magnesium 10, then, a waste material treatment unit 13 in combination with a protective gas G is used to introduce tiny magnesium alloy cuttings 2, by which ignition and a gas explosion are likely to be caused, into a refining chamber 111 having a mixing unit 12, a sinking whirlpool 121A generated by means of rotation of a stirrer 121 of the mixing unit 12 is used to rapidly carry the magnesium alloy cuttings 2 falling into the molten magnesium 10 to a bottom of the smelting furnace 11, so as to melt the magnesium alloy cuttings 2 and separate them from slag as soon as possible, and then, molten magnesium is tapped from a molten metal tapping chamber 112 and produced into magnesium ingots, to complete recycling of the magnesium alloy cuttings 2.

In the foregoing process, a rare earth refining agent can be fed into the molten magnesium 10 in the smelting furnace 11. Composition of the rare earth refining agent is 10% cerium oxide mixed with a DOW230 solvent, and an addition amount thereof is 1% of an addition quantity of the magnesium alloy cuttings. The rare earth refining agent helps to keep the molten magnesium 10 stable, to prevent the molten magnesium 10 in the melting furnace 11 from burning in a smelting process.

In an embodiment, to protect the smelting furnace 11 for safety during smelting, a protective gas is fed into the smelting furnace 11, and the protective gas is a gas mixture of sulfur hexafluoride SF₆ and air, where a flow rate of sulfur hexafluoride SF₆ is 25 cc/min, and a flow rate of air is 5 L/min.

Moreover, in another method embodiment of FIG. 2B, introducing, by the apparatus 1 for recycling magnesium alloy cuttings of the present invention, waste heat H of the smelting furnace 11 to the waste material treatment unit 13 to heat the magnesium alloy cuttings 2 is step S22B, and this step may be performed simultaneously with feeding the magnesium alloy cuttings 2 into the smelting furnace 11.

In conclusion, the method and apparatus for recycling magnesium alloy cuttings of the present invention have the following effects: 1. using a protective gas to cooperate with a feeding module, to avoid a gas explosion caused by spill-over and ignition of tiny magnesium alloy cuttings during a process of feeding magnesium alloy cuttings; 2. using a stirrer to generate a sinking whirlpool, to drive the magnesium alloy cuttings, after the magnesium alloy cuttings enter the furnace, to rapidly reach a bottom of the furnace to be molten and separated from slag; and 3. adding rare earth oxide into a refining agent to form a rare earth refining agent, to prevent occurrence of combustion during an operation process.

The foregoing are merely implementations or embodiments for technical measures taken in the present invention, and are not used to limit the scope of implementation of the present invention patent. Any equivalent changes and modifications having the meanings consistent with those of the claims of the present invention patent or made according to the claims of the present invention patent are covered by the scope of the present invention patent. 

What is claimed is:
 1. An apparatus for recycling magnesium alloy cuttings, wherein a structure thereof comprises: a smelting furnace, configured to hold molten magnesium, wherein the smelting furnace is segmented into a refining chamber and a molten metal tapping chamber in communication with each other; a mixing unit, rotatably disposed in the refining chamber, and configured to generate a sinking whirlpool toward a bottom of the smelting furnace during rotation; and a waste material treatment unit, comprising a feeding module, wherein the feeding module comprises a material rod capable of continuously rotating and a material channel in communication with the refining chamber, the material rod is configured to drive magnesium cuttings to enter the refining chamber through the material channel, and the material channel is configured to feed a protective gas.
 2. The apparatus for recycling magnesium alloy cuttings according to claim 1, wherein the waste material treatment unit further comprises a heating module and an air intake and dust collection module, wherein the heating module heats the feeding module, so as to preheat the magnesium alloy cuttings, and the air intake and dust collection module is disposed on the material channel and configured to recycle moisture and oil fume generated by the heated magnesium alloy cuttings.
 3. The apparatus for recycling magnesium alloy cuttings according to claim 2, wherein a heat energy source of the heating module is introduced from waste heat generated by the smelting furnace.
 4. The apparatus for recycling magnesium alloy cuttings according to claim 1, wherein the refining chamber is a cylindrical space.
 5. The apparatus for recycling magnesium alloy cuttings according to claim 1, wherein the refining chamber comprises a sloping bottom, having an end distal to the molten metal tapping chamber higher than an end proximal to the molten metal tapping chamber.
 6. The apparatus for recycling magnesium alloy cuttings according to claim 1, wherein the material rod is a screw mechanism.
 7. The apparatus for recycling magnesium alloy cuttings according to claim 1, wherein the protective gas is a gas mixture of nitrogen and carbon dioxide, wherein a proportion of nitrogen to carbon dioxide is 1:1.
 8. A method for recycling magnesium alloy cuttings, applied to the apparatus according to claim 1, comprising the following steps: feeding a protective gas into the smelting furnace holding molten magnesium, and adding a rare earth refining agent into the molten magnesium; feeding the protective gas into the material channel, and rotating, by the material rod, to drive magnesium cuttings to enter the refining chamber through the material channel; and rotating, by the mixing unit, to generate a sinking whirlpool, to drive the magnesium cuttings toward a bottom of the smelting furnace, and mixing and dissolving the magnesium cuttings into the molten magnesium, so that magnesium in the magnesium cuttings is separated from slag and magnesium floats upward to the molten metal tapping chamber.
 9. The method for recycling magnesium alloy cuttings according to claim 8, wherein the waste material treatment unit further comprises a heating module and an air intake and dust collection module, wherein while feeding the magnesium alloy cuttings into the refining chamber, waste heat of the smelting furnace is introduced to the waste material treatment unit to heat the magnesium alloy cuttings, and oil fume generated after heating the magnesium alloy cuttings is discharged into the air intake and dust collection module for waste gas treatment.
 10. The method for recycling magnesium alloy cuttings according to claim 8, wherein the protective gas fed into the smelting furnace is a gas mixture of sulfur hexafluoride and air, wherein a flow rate of sulfur hexafluoride is 25 cc/min, and a flow rate of air is 5 L/min.
 11. The method for recycling magnesium alloy cuttings according to claim 8, wherein the protective gas fed into the material channel is a gas mixture of nitrogen and carbon dioxide, wherein a flow rate of nitrogen is 1 L/min, and a flow rate of carbon dioxide is 1 L/min.
 12. The method for recycling magnesium alloy cuttings according to claim 8, wherein the rare earth refining agent may be rare earth, rare earth chloride, or rare earth oxide.
 13. The method for recycling magnesium alloy cuttings according to claim 8, wherein composition of the rare earth refining agent is 10% cerium oxide mixed with a DOW230 solvent, and an addition amount thereof is 1% of an addition quantity of the magnesium alloy cuttings. 